Problems have been encountered in service with pneumatic drum brakes and particularly constricting pneumatic drum brakes of the type having the inflatable tube disposed about the brake drum in keeping brake dust and foreign matter from entering the central hub region of the rotating drum.
In addition, in certain applications, such as for wind turbines, where electrical leads or components are disposed through the center region of the brake, it has been necessary to keep moisture, brake dust and foreign matter from such components. Where rotary seals are employed to prevent entry of moisture, brake dust and foreign matter from the central region of the brake, the need has arisen to provide access to the seals for replacement in service. In order to replace the seals, it has heretofore been necessary to completely disassemble the brake including the hub from the shaft or gearbox to which it is operatively connected, which, in situ, in wind turbine applications has been quite difficult and complex atop a tower and therefore quite costly. Thus, it has been desired to provide a pneumatic constricting drum brake with a sealed center hub and drum region where the seals may be readily accessed in service for replacement without complete disassembly of the brake and removal of the hub.